Hey guys, Fossil here in Tn.. Hopefully someone here can help us out. We have an older 225LC excavator and recently had the hydraulic pumps rebuilt and replaced a few hoses. After putting everything back together, we noticed a problem while operating it. When we curled the bucket in and out, and also when we crowded the "stick" (top boom section) in and out there is a point in the motion where the bucket and/or the stick hangs free. At this point, it stops moving for a few seconds, like there must be air in the hydraulic system, and then it starts to move again. We looked at the manual and tried bleeding all the bleeders which helped in the outward motion but we still have the pause when curling the bucket in or pulling the stick inward toward the cab. We have been told that it will get better if we just use it, but it hasn't. Any suggestions? Thanks
If it's a Komatsu like my PC200-6, there is a specific bleed sequence that needs to be followed to purge the air. I'm currently replacing a bunch of old hoses and I will have to get the book out to remind me how to do it again and what the sequence is. If I don't follow it correctly, it seems to take longer to get the air out.
Thanks Treemuncher. Our machine is a Cat 225LC and my son has bought a manual that was supposed to be for this machine, and others, but while going through the procedure for bleeding the system some of the info and pics are obviously for other models. We have other equipment and have found this to be the case when the manual is supposed to cover several different models, which can be a bit confusing. Makes you wonder which instructions/pics you can trust to be the same for our model.? We have bled every bleeder we can find, getting air out of some and not out of others. We aren't sure if it can damage something in the system or not to keep running it with the air in there. I would think, as with a brake system on a car, that as it is worked the air would eventually work its way to the bleeders. Anyway, thanks again for the reply.
I would think the air would eventually work its way back to tank if that's the problem. Is it possible that you are experiencing a region issue with oil flow? Maybe one of our mechanics here will know.
Thanks James. Not sure I know what "region issue" means.? During our bleeding attempts, we ended up curing part of the issue, but not all. And it is a bit confusing that it appears that one bleeder (which is supposed to bleed only one function cured two). The bleeder on the valve "block"/"body", or whatever it's called, that the manual says bleeds the bucket curling outward fixed that issue, but, at the same time it fixed the "stick" pushing outward function (which should be bled by a different bleeder). But we have bled all the bleeders (including the ones on the other side of the valve block, and directly across from the bleeder that fixed the outward function (which should bleed the opposing movement/function, with no results. So... we still have a few seconds hesitation on the inward/closing function on the bucket and the stick, while the outward/opening function is now fine. Sorry to muddy the waters and confuse everybody but having to do this by email/text etc. is hard to describe without over-complicating the matter. Once again, we are thankful for any and all help/suggestions since we have pretty much exhausted our resources.
Sounds good foss. Seems like it’s working out ok. On the regen issue I’m not an expert but I remember having a dead spot on the stick as it been pulled in on a normal dig cycle. Seems that there wasn’t enough oil flow getting back to stick creating that dead spot. I believe the newer machines re-route return oil that would normally go back to tank back to the stick to keep things functioning normal. Some machines have a valve that you can adjust to do this.
I have seen a few 235 cat excavators do a pause at the bottom of the arc of travel. It seems to take a second for the pump to catch up. This I thought was due to no regeneration circuit as the 300 series have It’s usually not a big issue when you are digging because the stick can’t free fall then.
Thanks to both of you. Both bits of info make sense and the machine has been run several hours since this started, with no apparent ill effects on the machine. Still can't figure why it never did this before the system was worked on,? Anyway, that gives us more fodder to chew on, and good part is, it is very useable as-is. Always great to get ideas/info from a community like this where people have actual experience.